Methods for event prioritization in network function virtualization using rule-based feedback

ABSTRACT

A method is implemented by an event collector to utilize feedback from an event handler to prioritize event forwarding to the event handler. The method includes receiving feedback from the event handler in response to a successful match-action in a rules engine, the feedback including a derived condition which is a generalized version of a condition stored in the match part of a rule, determining whether the derived condition is stored in an event prioritizer, and storing the derived condition in the event prioritizer with initial expiration timer and hit counter, in response to the derived condition not being present in the event prioritizer, and updating a hit counter and expiration timer of the derived condition in the event prioritizer, in response to the derived condition being present in the event prioritizer.

TECHNICAL FIELD

Embodiments of the invention relate to the field of network functionvirtualization; and more specifically, to managing the prioritization ofevents related to network function virtualization.

BACKGROUND ART

Network function virtualization (NFV) is a technology that appliesvirtualization to the operation of network nodes. NFV can virtualizenetwork device functions to separate them from the operation of a givennetwork device and its hardware. The network device functions can thenbe executed local to or remote from the associated network device.

A virtualized network function, or VNF, may consist of one or morevirtual machines running different software and processes, on top of ageneral computing system, a set of servers, switches, and/or storagedevices. VNF can be distributed and implemented in a cloud computingenvironment. In this way the functions of a network node do not requirehaving custom specialized hardware components to implement each networkfunction.

VNF provides advantages in resource utilization that enable networkfunctions to be executed in a location with more optimal use ofresources within the network. For example, more complicated or resourceintensive network functions can be executed at a data center instead ofat a network device enabling the network device to utilize fewerresources and thereby reducing the component cost of the network device.

However, VNF creates additional communication overhead to relay data toand from the network device as the VNF functions are executed remotely.The additional infrastructure for managing VNF reduces some of the gainsin computing efficiency and can increase bandwidth utilization in anetwork.

SUMMARY

In one embodiment, a method is implemented by an event collector toutilize feedback from an event handler to prioritize event forwarding tothe event handler. The method includes receiving feedback from the eventhandler in response to a successful match-action in a rules engine, thefeedback including a derived condition which is a generalized version ofa condition stored in the match part of a rule, determining whether thederived condition is stored in an event prioritizer, and storing thederived condition in the event prioritizer with initial expiration timerand hit counter, in response to the derived condition not being presentin the event prioritizer, and updating a hit counter and expirationtimer of the derived condition in the event prioritizer, in response tothe derived condition being present in the event prioritizer.

In another embodiment, a computing device implements a method of anevent collector to utilize feedback from an event handler to prioritizeevent forwarding to the event handler. The computing device includes anon-transitory machine-readable medium having stored therein the eventcollector, and a processor coupled to the non-transitorymachine-readable medium. The processor executes the event collector. Theevent collector receives feedback from the event handler in response toa successful match-action in a rules engine. The feedback includes aderived condition which is a generalized version of a condition storedin the match part of a rule. The event collector determines whether thederived condition is stored in an event prioritizer, stores the derivedcondition in the event prioritizer with initial expiration timer and hitcounter, in response to the derived condition not being present in theevent prioritizer, and updates the hit counter and the expiration timerof the derived condition in the event prioritizer, in response to thederived condition being present in the event prioritizer.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may best be understood by referring to the followingdescription and accompanying drawings that are used to illustrateembodiments of the invention. In the drawings:

FIG. 1 is a diagram of one embodiment of a network functionvirtualization architecture.

FIG. 2 is a block diagram of one embodiment of the event handler andevent collector.

FIG. 3 is a diagram of one example embodiment of a process sequencebetween the orchestrated infrastructure 205, event collector 203, and anevent handler 201.

FIG. 4 is a diagram of one embodiment of a process of the event handlerand event collector device.

FIG. 5 is a diagram of one embodiment of a process for event handling.

FIG. 6 is a diagram of one embodiment of the operation of the eventcollector to forward events.

FIG. 7A illustrates connectivity between network devices (NDs) within anexemplary network, as well as three exemplary implementations of theNDs, according to some embodiments of the invention.

FIG. 7B illustrates an exemplary way to implement a special-purposenetwork device according to some embodiments of the invention.

FIG. 7C illustrates various exemplary ways in which virtual networkelements (VNEs) may be coupled according to some embodiments of theinvention.

FIG. 7D illustrates a network with a single network element (NE) on eachof the NDs, and within this straight forward approach contrasts atraditional distributed approach (commonly used by traditional routers)with a centralized approach for maintaining reachability and forwardinginformation (also called network control), according to some embodimentsof the invention.

FIG. 7E illustrates the simple case of where each of the NDs implementsa single NE, but a centralized control plane has abstracted multiple ofthe NEs in different NDs into (to represent) a single NE in one of thevirtual network(s), according to some embodiments of the invention.

FIG. 7F illustrates a case where multiple VNEs are implemented ondifferent NDs and are coupled to each other, and where a centralizedcontrol plane has abstracted these multiple VNEs such that they appearas a single VNE within one of the virtual networks, according to someembodiments of the invention.

FIG. 8 illustrates a general-purpose control plane device withcentralized control plane (CCP) software 850), according to someembodiments of the invention.

DETAILED DESCRIPTION

The following description describes methods and apparatus for improvingthe operation of event handling for network function virtualization. Theimproved event handling includes a method by which an event collectorgathers feedback from an external event handler to create a datastructure that is used to prioritize event forwarding to the same eventhandler. Feedback from the event handler is sent to the event collectorupon a successful match-action in a rules engine. The feedback containsa generalized version of the condition stored in the match part of arule. The event collector stores these generalized conditions in a datastructure (e.g., an event prioritizer), along with expiration timers andhit counters for each entry. In some embodiments, expiration timers maynot be utilized. Expiration timers are reset when the same generalizedcondition is received more than once. Hit counters are increased eachtime the generalized condition is received. The event collector may keepthe size of this data structure limited to a certain number ofgeneralized conditions, using the expiration timers or other means toachieve this. The event collector uses the sum, mean, median, mode, orsimilar function of the hit counters for all generalized conditions inthe event prioritizer matching an event to determine the priority ofthat event. The event collector keeps the incoming events in priorityqueues for internal processing or external dispatching, using eventpriority assigned by the event prioritizer to determine the order inwhich the events are dequeued and processed/forwarded (e.g., the higherthe priority, the sooner the event is processed/forwarded).

In the following description, numerous specific details such as logicimplementations, opcodes, means to specify operands, resourcepartitioning/sharing/duplication implementations, types andinterrelationships of system components, and logicpartitioning/integration choices are set forth in order to provide amore thorough understanding of the present invention. It will beappreciated, however, by one skilled in the art that the invention maybe practiced without such specific details. In other instances, controlstructures, gate level circuits and full software instruction sequenceshave not been shown in detail in order not to obscure the invention.Those of ordinary skill in the art, with the included descriptions, willbe able to implement appropriate functionality without undueexperimentation.

References in the specification to “one embodiment,” “an embodiment,”“an example embodiment,” etc., indicate that the embodiment describedmay include a particular feature, structure, or characteristic, butevery embodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed.

Bracketed text and blocks with dashed borders (e.g., large dashes, smalldashes, dot-dash, and dots) may be used herein to illustrate optionaloperations that add additional features to embodiments of the invention.However, such notation should not be taken to mean that these are theonly options or optional operations, and/or that blocks with solidborders are not optional in certain embodiments of the invention.

In the following description and claims, the terms “coupled” and“connected,” along with their derivatives, may be used. It should beunderstood that these terms are not intended as synonyms for each other.“Coupled” is used to indicate that two or more elements, which may ormay not be in direct physical or electrical contact with each other,co-operate or interact with each other. “Connected” is used to indicatethe establishment of communication between two or more elements that arecoupled with each other.

An electronic device stores and transmits (internally and/or with otherelectronic devices over a network) code (which is composed of softwareinstructions and which is sometimes referred to as computer program codeor a computer program) and/or data using machine-readable media (alsocalled computer-readable media), such as machine-readable storage media(e.g., magnetic disks, optical disks, solid state drives, read onlymemory (ROM), flash memory devices, phase change memory) andmachine-readable transmission media (also called a carrier) (e.g.,electrical, optical, radio, acoustical or other form of propagatedsignals—such as carrier waves, infrared signals). Thus, an electronicdevice (e.g., a computer) includes hardware and software, such as a setof one or more processors (e.g., wherein a processor is amicroprocessor, controller, microcontroller, central processing unit,digital signal processor, application specific integrated circuit, fieldprogrammable gate array, other electronic circuitry, a combination ofone or more of the preceding) coupled to one or more machine-readablestorage media to store code for execution on the set of processorsand/or to store data. For instance, an electronic device may includenon-volatile memory containing the code since the non-volatile memorycan persist code/data even when the electronic device is turned off(when power is removed), and while the electronic device is turned onthat part of the code that is to be executed by the processor(s) of thatelectronic device is typically copied from the slower non-volatilememory into volatile memory (e.g., dynamic random access memory (DRAM),static random access memory (SRAM)) of that electronic device. Typicalelectronic devices also include a set or one or more physical networkinterface(s) (NI(s)) to establish network connections (to transmitand/or receive code and/or data using propagating signals) with otherelectronic devices. For example, the set of physical NIs (or the set ofphysical NI(s) in combination with the set of processors executing code)may perform any formatting, coding, or translating to allow theelectronic device to send and receive data whether over a wired and/or awireless connection. In some embodiments, a physical NI may compriseradio circuitry capable of receiving data from other electronic devicesover a wireless connection and/or sending data out to other devices viaa wireless connection. This radio circuitry may include transmitter(s),receiver(s), and/or transceiver(s) suitable for radiofrequencycommunication. The radio circuitry may convert digital data into a radiosignal having the appropriate parameters (e.g., frequency, timing,channel, bandwidth, etc.). The radio signal may then be transmitted viaantennas to the appropriate recipient(s). In some embodiments, the setof physical NI(s) may comprise network interface controller(s) (NICs),also known as a network interface card, network adapter, or local areanetwork (LAN) adapter. The NIC(s) may facilitate in connecting theelectronic device to other electronic devices allowing them tocommunicate via wire through plugging in a cable to a physical portconnected to a NIC. One or more parts of an embodiment of the inventionmay be implemented using different combinations of software, firmware,and/or hardware.

A network device (ND) is an electronic device that communicativelyinterconnects other electronic devices on the network (e.g., othernetwork devices, end-user devices). Some network devices are “multipleservices network devices” that provide support for multiple networkingfunctions (e.g., routing, bridging, switching, Layer 2 aggregation,session border control, Quality of Service, and/or subscribermanagement), and/or provide support for multiple application services(e.g., data, voice, and video).

FIG. 1 is a diagram of one embodiment of a network functionvirtualization architecture. The illustrated network functionvirtualization (NFV) architecture is provided by way of example toillustrate a context for the embodiments. The NFV architecture includesan NFV management and orchestration (NFV MANO) architecture (e.g., theNFV MANO defined by the European Telecommunications Standards Institute(ETSI) NFV working group). The NFV MANO organizes the life-cyclemanagement of virtual network functions (VNFs) in cloud and similarcomputing environments.

The NFV MANO is organized with different functional blocks. Events areused by different functional blocks to determine the actions to be takenusing the available virtualized resources. An event can be any messagethat conveys some indicator-related data (e.g.: VNF load is at 50%,memory consumption is at 95% of capacity, or similar information).

The NFV MANO 101 manages VNFs 103 and associated components. Thesecomponents include element management (EM) 105. The EM 105 providesconfiguration, fault management, accounting, collection and security fora VNF 103. The EM 105 can receive events and other information relevantto its tasks from the VNF manager (VNFM) 107 that relate to theunderlying virtualized resources. The EM 104 sends events to the VNFM107 based on data collected from the VNF 103.

The VNFM 107 manages the lifecycle of one or more VNF instances 103. TheVNFM receives events from the underlying infrastructure (e.g., from oneor more virtualized infrastructure managers (VIMs) 113) and from the EM105 with information related to the VNFs 103. The VNFM 107 can also usethis information to take actions (e.g.: healing, scaling, andconfiguration).

The Network Function Virtualization Orchestrator (NFVO) 109 manages andorchestrates the network services, which includes one or more VNFs 103and the connectivity between them. In some embodiments, policies governthe NFVO behavior. The NFVO can receive events from the VNFM 107 andtake actions considering rules defined by the operations supportsystems/business support systems (OSS/BSS) layer 111. These functionalblocks of the NFV architecture are connected through reference points(e.g., a representation state transfer (REST) interface). NFV events mayoccur in the VNF 103, or in its underlying (virtualized) infrastructure.For example, NFV events can be transported through the Ve-Vnfm referencepoint, which can be split into Ve-Vnfm-em and Ve-Vnfm-vnf.

The reference points, such as the Ve-Vnfm reference point, describes aset of application programming interfaces (APIs). For example, five APIsmay service the Ve-Vnfm reference point, of which three of these APIsmay generate VNF events. In this example, a performance management eventcan be generated from the VNFM 107 to the EM 105, a fault managementevent from the VNFM 107 to the EM 105, and an indicator from the EM 105or VNF 103 to the VNFM 107.

The Or-Vnfm reference point defines how event information collected viathe Ve-Vnfm reference point is sent to the NFVO 109. The VNFM 107 may dosome aggregation or correlation and then forward this event informationto the NFVO 109 via the Or-Vnfm reference point. The VNFM 107 can beconsidered to behave as a proxy for events from the underlying VNFs 103and VNFI 113. Thus, the NFV MANO allows for event notifications to flowin different directions to different components (e.g.: from the VNFM 107to EM 105, from the EM 105 to VNFM 107, from the VNFM 107 to the NFVO109 and similar event movements). This means that more centralizedcomponents (e.g.: NFVO 109) may end up receiving a great volume ofevents from different orchestrated resources (e.g.: VNFs 103, networkservices, network function virtualization infrastructure (NFVI) 115resources).

The NFVO 109 can utilize policies or rules to determine reaction tochanges in network conditions. The enforcement of these policies andrules can be done by a rule engine. The rules engine works by checkingconditions (e.g.: when an event or some other trigger happens) andtaking actions when the condition is satisfied. Rules can evolve to becomplex and interdependent. In some embodiments, the NFVO 109 includes aunified event collection and streaming implementation called VNF EventStreaming (VES).

The NFVI 115 is composed of points of presence where VNFs 103 aredeployed. NFVI 115 works with the VNFs 103 and VIMs 113 to provide theresources for the VNFs 103 to execute. NFVI 115 provides avirtualization layer over the hardware to abstract hardware resourcesthat can be utilized by the VNFs 103. The hardware resources can bedistributed over multiple computing or networking devices.

The NFV architecture present several problems for event handling. An NFVentity that collects events from many sources (e.g.: VNFM) 107 willtypically receive and aggregate many events for its managed resources(e.g.: VNFs 103/Ems 105 and VIMs 113). These events may be of aconsiderable volume in larger NFV infrastructures. It is in the bestinterest of service providers to maximize the handling capability ofsuch events, optimizing the response time, that is, reducing the timebetween an event happens and orchestration decisions are taken based onits information. However, current NFV architecture is unable to thisgoal. The embodiments achieve the goal, such that important events areprioritized and forwarded from the event collector (e.g.: VNFM 107) tothe event handler (e.g.: NFVO 109).

In addition, networks and network infrastructure are dynamic.Orchestration rules (or policies) may often shift in the networkinfrastructure, causing events that are relevant at one time to be lessrelevant at a subsequent time. Thus, pre-assigning static priorities toevents on the VNFM 107 is not ideal, since the system would not be ableto respond to environmental changes dynamically (e.g.: a given type ofevent becomes more relevant with a change in orchestration policies).The existing NFV MANO framework does not provide a prioritization schemefor events.

The embodiments overcome the limitations of the art and address theabove-mentioned issues. The embodiments provide a method in which anevent handler (e.g.: NFVO 109) guides the event collector (e.g.: VNFM107) on which events lead to decisions in the network and instructing(or hinting) at what event types should be prioritized. This hinting isbased on matched rules in a rules engine, which the event handler canutilize. For example, an NFVO 109 may receive a large number of eventsabout bandwidth utilization from all VNFs 103 through the VNFM 107, butthey are only relevant (e.g.: used for scaling-up/down) for a given typeof VNF X in region Y.

To solve the forwarding priority, the embodiments provide a priorityqueue. The priority queues may be implemented in any form (e.g., using aheap-based data structure). The event collector and the event handlerinteraction may be brokered by the configurable priority queue to helpforward important events first. Event priority will be assigned in theevent collector based on information relayed by the event handler, andhigher priority events are processed (and optionallyaggregated/correlated) and forwarded first.

To address dynamic environments with changing rules, the embodimentsprovide a mechanism in which the event handler is constantly providinghints (feedback) to the event collector, so that the priority queues canauto-adjust. This feedback is generated in the event handler, based onconditions obtained from the rules engine when actions are taken for agiven rule. In other words, whenever a rule is used (matched) because ofan event, the event collector is informed about this so that it can tuneits behavior. The event collector will keep a data structure responsiblefor matching incoming events and assigning priorities to them.

The embodiments provide advantages over the prior art. The embodimentsenable an NFV system to dynamically prioritize events, based on the useof rules engines. The advantages include reduced response times forimportant events in the network; adaptability to changing networkconditions, so that the prioritization does not become obsolete; lowoverhead, since the embodiments use low complexity and optimized datastructures and algorithms instead of more complex, harder to implementlearning systems.

FIG. 2 is a block diagram of one embodiment of the event handler andevent collector. The diagram illustrates the relationship between theelements of the event handler 201 and the event collector 203 as well asother components. The event handler 201 and the event collector 203 canbe any event handling component and any event collecting component inthe NFV architecture. These components can be in communication with theother components of the NFV architecture via the orchestratedinfrastructure 205.

The event handler 201 includes an action processing component 209, arules engine 211, and an event processing component 213. The operationof these components is described herein below with relation to FIGS.3-6. The rules engine 211 is in communication with a rules database 207which can have any format and be any type of database capable of storingand retrieving rules to be applied by the rules engine 211. These rulescan define a set of criteria for a correlated action or set of actionsto be taken. A ‘set,’ as used herein, refers to any positive wholenumber of items including one item. Rules can encompass policies definedby a system administrator, derived conditions as discussed herein andsimilar types of rules. The event collector 203 includes an eventcollection component 217 and an event prioritization component 215.Similarly, the operation of these components is described herein belowwith relation to FIGS. 3-6.

The operations in the flow diagrams will be described with reference tothe exemplary embodiments of the other figures. However, it should beunderstood that the operations of the flow diagrams can be performed byembodiments of the invention other than those discussed with referenceto the other figures, and the embodiments of the invention discussedwith reference to these other figures can perform operations differentthan those discussed with reference to the flow diagrams.

The components of the NFV architecture that function as the even handlerdevice 201 and the event collector 203 can be implemented at specificcomputing or network devices or can be implemented in a cloud computingenvironment. All functions and components may be subject tovirtualization (e.g.: the NFVO can run in a separate node from theVNFM). This does not alter the inner working of the embodiment but mayhave an impact on how the interfaces implementing the reference pointsare implemented (e.g.: a remote REST interface vs. direct functioncalls).

FIG. 3 is a diagram of one example embodiment of a process sequencebetween the orchestrated infrastructure 205, event collector 203, and anevent handler 201. The process of the embodiments can be initiated inresponse to the orchestrated infrastructure 205 generating an event thatis sent initially to an event collector 203. The event collector 203 canclean up expired or derived conditions based on timers, assign eventpriority based on event prioritizer, and store the event in the properpriority queue. The event collector retrieves a next event from thepriority queue and dispatches the event to the event handler 201. Theevent handler 201 processes the event based on matched rules determinedby the rules engine. The event handler 201 can also determine derivedconditions for the matched rules and provide this as feedback to theevent collector 203. The event collector 203 then updates eventprioritization for the derived condition. This sequence is described ingreater detail with reference to FIGS. 4-6.

FIG. 4 is a diagram of one embodiment of a process of the event handlerand event collector device. The event handler operates in response toreceiving an event and performs an action on this event (Block 401). Theevent handler can be any component of the NFV architecture that iscapable of processing events. Similarly, the event collector can be anycomponent of the NFV architecture capable of generating and/orcollecting and forwarding events. In some embodiments, the event handlerapplies pre-processing of the received event (Block 403). Pre-processingof events can include filtering events, adapting or modifying events orsimilar actions that can be applied to all events or certain eventsbased on type, origin or similar criteria.

The event handler (e.g., an NFVO) processes an event from the eventcollector (e.g., VNFM), and based on processing of the event by a rulesengine, decides to take an action in the network based on that event ifthe event matched one or more rules (Block 405). For example, the NFVOmay have decided to scale-up a VNF (i.e.: create another instance of theVNF), because the NFVO received an event that triggered a rule's action.A rule will be composed of a match condition, and an action, because theNFVO implements a rules engine that has a defined set of rules to beapplied to received events. In one example, the rule could be “if oneVNF in region X has 5 or more observations of more than 85% of CPU usage(condition), another instance of the same VNF is to be created(action).”

In addition, the event handler sends feedback to the event collector(Block 407). For example, every time the NFVO uses an event to take anaction, the NFVO can send back to the VNFM a special derivation of thecondition of the rule that was matched. This feedback information isreferred to herein as a “derived condition” that can match incomingevents from the VNFs and the VIMs. This derived condition may bepre-configured for each rule, or it may be obtained by a heuristic thattransforms the original condition into its derived form, for example, byremoving scalars and aggregation information from the originalcondition.

Continuing the previous example above, the original condition used bythe NFVO is “if one VNF in region X has 5 or more observations of morethan 85% of CPU usage.” The derived condition in this case is then “ifevent is about CPU usage of a VNF in region X.” In other words, scalarconditional elements (“more than 85% of usage”) andaggregation/correlation elements (“has 5 or more observations”) wereremoved from the original condition, so that only a generic condition isderived. In some embodiments, this derived condition is alsopre-configured by an operator for every rule, so that no derivationprocess is necessary. The method of derivation can have differentcharacteristics depending on the NFV architectural environment and theoperator's intent.

The event collector manages the feedback received from the event handler(Block 451). The event collector can store the derived condition with ahit counter and an expiration timer in a data structure called the eventprioritizer. The type of this data structure may include, but is notlimited to, a list of derived conditions, a managed tree structure, orsimilar data structure. This data structure enables the event collectorto assess whether an incoming event matches a pattern seen before, basedon feedback and configuration from the event handler.

The implementation of the expiration timer can be dependent on thearchitecture of the event collector. If an event-driven architecture isused, the expiration time can be a timer registered in an event loop. Inother architectures, a timestamp-based mechanism may be used forskipping and removing derived conditions upon verification when an eventis received, or for periodically cleaning up the event prioritizer. Bymeans of this expiration timer, the event prioritizer acts as atime-aware least recently used cache (TLRU). In some embodiments, theevent prioritizer can also be limited to a certain size, to avoid costlylookups that could compromise performance. Hit counter values obtainedfrom the event prioritizer are used to determine the priority of anevent. The events themselves are stored in the priority queue, asdescribed further herein below.

The event collector also manages rule renewal and expiration using theevent prioritizer. When the event collector receives a derived conditionfrom the event handler (Block 453), the event collector checks whetherthe derived condition is already stored in the event prioritizer (Block455). If a derived condition does exist in the event prioritizer, thenits expiration timer is reset and the hit counter is increased (Block459). If the derived condition is not present in the event prioritizer,then the derived condition is added to the event prioritizer and theexpiration timer is set to a default value and the hit counter is set toone (Block 457).

Rules whose expiration timer is reached are removed. This makes thesystem behavior dynamic. The expiration timer mechanism guarantees thatthe event prioritizer does not become overloaded or stale. In otherembodiments, the event prioritizer can use other mechanisms to removestale or unused rules.

FIG. 5 is a diagram of one embodiment of a process for event handling.The process can be trigger in response to a new event being received bythe event collector (Block 501). When new events occur in the NFVarchitecture and are received by the event collector they are matchedagainst a set of derived conditions stored in the event prioritizer bythe event collection agent (Block 503). If the received event matches aderived condition or similar rules stored in the event prioritizer(e.g.: a CPU notification from a VNF in region X), the hit counterassociated with that derived condition is used to determine the priorityof the event. If an event matches more than one derived condition orrule, then the value used for the prioritization is a function of thecounters of all matched rules (Block 505). The function can be a sum ofthe counters, a mean, a median, a mode or similar function applied tothe counters to derive an event priority value.

The received event is then to be stored in one of a set of priorityqueues (Block 509). The priority queues can be a heap-like datastructure that is sorted by the priority value that is assigned to theevent. The priority queue can be used for picking the next event to beprocessed either for internal purposes of the event collector (e.g.,aggregation/correlation), or for the eventual dispatch to the eventhandler.

More than one priority queue can be in use in the event collectingdevice at a time for any purposes as long as the priority of storedevents is based on the output of the event prioritizer, and as long asthese priority queues have a strict order (e.g.: events in queue A arealways served before those from queue B). The event collection agentdetermines which of the available priority queues to place an event inbased on any configurable criteria (Block 507). In one example, multiplepriority queues can be utilized to avoid event starvation. If onlyhigh-priority events are handled, low priority ones may never beprocessed. An event collector may choose to dedicate part of the time(e.g.: 70%) to deal with high-priority events in one queue, and asmaller amount of time (e.g.: 30%) to dedicate to low-priority eventsstored in another queue.

FIG. 6 is a diagram of one embodiment of the operation of the eventcollector to forward events. When the event collector detects the needfor sending an event (Block 601), then one of the priority queues ischosen (Block 603). In one example the event collector includes anasynchronous event loop that determines when it is time to send anevent. In some cases, there is an explicit request from an event handlerthat is serviced by the event collector. In one example, the eventcollection agent can implement a pre-configured policy, such as the70%-30% split mentioned in the above-example. The event collection agentselects the event with the highest priority from the selected priorityqueue and sends the selected event to the event handler (Block 605).

FIG. 7A illustrates connectivity between network devices (NDs) within anexemplary network, as well as three exemplary implementations of theNDs, according to some embodiments of the invention. FIG. 7A shows NDs700A-H, and their connectivity by way of lines between 700A-700B,700B-700C, 700C-700D, 700D-700E, 700E-700F, 700F-700G, and 700A-700G, aswell as between 700H and each of 700A, 700C, 700D, and 700G. These NDsare physical devices, and the connectivity between these NDs can bewireless or wired (often referred to as a link). An additional lineextending from NDs 700A, 700E, and 700F illustrates that these NDs actas ingress and egress points for the network (and thus, these NDs aresometimes referred to as edge NDs; while the other NDs may be calledcore NDs).

Two of the exemplary ND implementations in FIG. 7A are: 1) aspecial-purpose network device 702 that uses custom application-specificintegrated-circuits (ASICs) and a special-purpose operating system (OS);and 2) a general-purpose network device 704 that uses commonoff-the-shelf (COTS) processors and a standard OS.

The special-purpose network device 702 includes networking hardware 710comprising a set of one or more processor(s) 712, forwarding resource(s)714 (which typically include one or more ASICs and/or networkprocessors), and physical network interfaces (NIs) 716 (through whichnetwork connections are made, such as those shown by the connectivitybetween NDs 700A-H), as well as non-transitory machine readable storagemedia 718 having stored therein networking software 720. Duringoperation, the networking software 720 may be executed by the networkinghardware 710 to instantiate a set of one or more networking softwareinstance(s) 722. Each of the networking software instance(s) 722, andthat part of the networking hardware 710 that executes that networksoftware instance (be it hardware dedicated to that networking softwareinstance and/or time slices of hardware temporally shared by thatnetworking software instance with others of the networking softwareinstance(s) 722), form a separate virtual network element 730A-R. Eachof the virtual network element(s) (VNEs) 730A-R includes a controlcommunication and configuration module 732A-R (sometimes referred to asa local control module or control communication module) and forwardingtable(s) 734A-R, such that a given virtual network element (e.g., 730A)includes the control communication and configuration module (e.g.,732A), a set of one or more forwarding table(s) (e.g., 734A), and thatportion of the networking hardware 710 that executes the virtual networkelement (e.g., 730A). The networking software 720 can include the eventhandler and/or event collector 765 as described herein as part of theNFV software and infrastructure.

The special-purpose network device 702 is often physically and/orlogically considered to include: 1) a ND control plane 724 (sometimesreferred to as a control plane) comprising the processor(s) 712 thatexecute the control communication and configuration module(s) 732A-R;and 2) a ND forwarding plane 726 (sometimes referred to as a forwardingplane, a data plane, or a media plane) comprising the forwardingresource(s) 714 that utilize the forwarding table(s) 734A-R and thephysical NIs 716. By way of example, where the ND is a router (or isimplementing routing functionality), the ND control plane 724 (theprocessor(s) 712 executing the control communication and configurationmodule(s) 732A-R) is typically responsible for participating incontrolling how data (e.g., packets) is to be routed (e.g., the next hopfor the data and the outgoing physical NI for that data) and storingthat routing information in the forwarding table(s) 734A-R, and the NDforwarding plane 726 is responsible for receiving that data on thephysical NIs 716 and forwarding that data out the appropriate ones ofthe physical NIs 716 based on the forwarding table(s) 734A-R.

FIG. 7B illustrates an exemplary way to implement the special-purposenetwork device 702 according to some embodiments of the invention. FIG.7B shows a special-purpose network device including cards 738 (typicallyhot pluggable). While in some embodiments the cards 738 are of two types(one or more that operate as the ND forwarding plane 726 (sometimescalled line cards), and one or more that operate to implement the NDcontrol plane 724 (sometimes called control cards)), alternativeembodiments may combine functionality onto a single card and/or includeadditional card types (e.g., one additional type of card is called aservice card, resource card, or multi-application card). A service cardcan provide specialized processing (e.g., Layer 4 to Layer 7 services(e.g., firewall, Internet Protocol Security (IPsec), Secure SocketsLayer (SSL)/Transport Layer Security (TLS), Intrusion Detection System(IDS), peer-to-peer (P2P), Voice over IP (VoIP) Session BorderController, Mobile Wireless Gateways (Gateway General Packet RadioService (GPRS) Support Node (GGSN), Evolved Packet Core (EPC) Gateway)).By way of example, a service card may be used to terminate IPsec tunnelsand execute the attendant authentication and encryption algorithms.These cards are coupled together through one or more interconnectmechanisms illustrated as backplane 736 (e.g., a first full meshcoupling the line cards and a second full mesh coupling all of thecards).

Returning to FIG. 7A, the general-purpose network device 704 includeshardware 740 comprising a set of one or more processor(s) 742 (which areoften COTS processors) and physical NIs 746, as well as non-transitorymachine-readable storage media 748 having stored therein software 750.During operation, the processor(s) 742 execute the software 750 toinstantiate one or more sets of one or more applications 764A-R. Thesoftware 750 can include the event handler and/or event collector 765 asdescribed herein as part of the NFV software and infrastructure. Whileone embodiment does not implement virtualization, alternativeembodiments may use different forms of virtualization. For example, inone such alternative embodiment the virtualization layer 754 representsthe kernel of an operating system (or a shim executing on a baseoperating system) that allows for the creation of multiple instances762A-R called software containers that may each be used to execute one(or more) of the sets of applications 764A-R; where the multiplesoftware containers (also called virtualization engines, virtual privateservers, or jails) are user spaces (typically a virtual memory space)that are separate from each other and separate from the kernel space inwhich the operating system is run; and where the set of applicationsrunning in a given user space, unless explicitly allowed, cannot accessthe memory of the other processes. In another such alternativeembodiment the virtualization layer 754 represents a hypervisor(sometimes referred to as a virtual machine monitor (VMM)) or ahypervisor executing on top of a host operating system, and each of thesets of applications 764A-R is run on top of a guest operating systemwithin an instance 762A-R called a virtual machine (which may in somecases be considered a tightly isolated form of software container) thatis run on top of the hypervisor—the guest operating system andapplication may not know they are running on a virtual machine asopposed to running on a “bare metal” host electronic device, or throughpara-virtualization the operating system and/or application may be awareof the presence of virtualization for optimization purposes. In yetother alternative embodiments, one, some or all of the applications areimplemented as unikernel(s), which can be generated by compilingdirectly with an application only a limited set of libraries (e.g., froma library operating system (LibOS) including drivers/libraries of OSservices) that provide the particular OS services needed by theapplication. As a unikernel can be implemented to run directly onhardware 740, directly on a hypervisor (in which case the unikernel issometimes described as running within a LibOS virtual machine), or in asoftware container, embodiments can be implemented fully with unikernelsrunning directly on a hypervisor represented by virtualization layer754, unikernels running within software containers represented byinstances 762A-R, or as a combination of unikernels and theabove-described techniques (e.g., unikernels and virtual machines bothrun directly on a hypervisor, unikernels and sets of applications thatare run in different software containers).

The instantiation of the one or more sets of one or more applications764A-R, as well as virtualization if implemented, are collectivelyreferred to as software instance(s) 752. Each set of applications764A-R, corresponding virtualization construct (e.g., instance 762A-R)if implemented, and that part of the hardware 740 that executes them (beit hardware dedicated to that execution and/or time slices of hardwaretemporally shared), forms a separate virtual network element(s) 760A-R.

The virtual network element(s) 760A-R perform similar functionality tothe virtual network element(s) 730A-R—e.g., similar to the controlcommunication and configuration module(s) 732A and forwarding table(s)734A (this virtualization of the hardware 740 is sometimes referred toas network function virtualization (NFV)). Thus, NFV may be used toconsolidate many network equipment types onto industry standardhigh-volume server hardware, physical switches, and physical storage,which could be located in Data centers, NDs, and customer premiseequipment (CPE). While embodiments of the invention are illustrated witheach instance 762A-R corresponding to one VNE 760A-R, alternativeembodiments may implement this correspondence at a finer levelgranularity (e.g., line card virtual machines virtualize line cards,control card virtual machine virtualize control cards, etc.); it shouldbe understood that the techniques described herein with reference to acorrespondence of instances 762A-R to VNEs also apply to embodimentswhere such a finer level of granularity and/or unikernels are used.

In certain embodiments, the virtualization layer 754 includes a virtualswitch that provides similar forwarding services as a physical Ethernetswitch. Specifically, this virtual switch forwards traffic betweeninstances 762A-R and the physical NI(s) 746, as well as optionallybetween the instances 762A-R; in addition, this virtual switch mayenforce network isolation between the VNEs 760A-R that by policy are notpermitted to communicate with each other (e.g., by honoring virtuallocal area networks (VLANs)).

The third exemplary ND implementation in FIG. 7A is a hybrid networkdevice 706, which includes both custom ASICs/special-purpose OS and COTSprocessors/standard OS in a single ND or a single card within an ND. Incertain embodiments of such a hybrid network device, a platform VM(i.e., a VM that that implements the functionality of thespecial-purpose network device 702) could provide forpara-virtualization to the networking hardware present in the hybridnetwork device 706.

Regardless of the above exemplary implementations of an ND, when asingle one of multiple VNEs implemented by an ND is being considered(e.g., only one of the VNEs is part of a given virtual network) or whereonly a single VNE is currently being implemented by an ND, the shortenedterm network element (NE) is sometimes used to refer to that VNE. Also,in all of the above exemplary implementations, each of the VNEs (e.g.,VNE(s) 730A-R, VNEs 760A-R, and those in the hybrid network device 706)receives data on the physical NIs (e.g., 716, 746) and forwards thatdata out the appropriate ones of the physical NIs (e.g., 716, 746). Forexample, a VNE implementing IP router functionality forwards IP packetson the basis of some of the IP header information in the IP packet;where IP header information includes source IP address, destination IPaddress, source port, destination port (where “source port” and“destination port” refer herein to protocol ports, as opposed tophysical ports of a ND), transport protocol (e.g., user datagramprotocol (UDP), Transmission Control Protocol (TCP), and differentiatedservices code point (DSCP) values.

FIG. 7C illustrates various exemplary ways in which VNEs may be coupledaccording to some embodiments of the invention. FIG. 7C shows VNEs770A.1-770A.P (and optionally VNEs 770A.Q-770A.R) implemented in ND 700Aand VNE 770H.1 in ND 700H. In FIG. 7C, VNEs 770A.1-P are separate fromeach other in the sense that they can receive packets from outside ND700A and forward packets outside of ND 700A; VNE 770A.1 is coupled withVNE 770H.1, and thus they communicate packets between their respectiveNDs; VNE 770A.2-770A.3 may optionally forward packets between themselveswithout forwarding them outside of the ND 700A; and VNE 770A.P mayoptionally be the first in a chain of VNEs that includes VNE 770A.Qfollowed by VNE 770A.R (this is sometimes referred to as dynamic servicechaining, where each of the VNEs in the series of VNEs provides adifferent service—e.g., one or more layer 4-7 network services). WhileFIG. 7C illustrates various exemplary relationships between the VNEs,alternative embodiments may support other relationships (e.g.,more/fewer VNEs, more/fewer dynamic service chains, multiple differentdynamic service chains with some common VNEs and some different VNEs).

The NDs of FIG. 7A, for example, may form part of the Internet or aprivate network; and other electronic devices (not shown; such as enduser devices including workstations, laptops, netbooks, tablets, palmtops, mobile phones, smartphones, phablets, multimedia phones, VoiceOver Internet Protocol (VOIP) phones, terminals, portable media players,GPS units, wearable devices, gaming systems, set-top boxes, Internetenabled household appliances) may be coupled to the network (directly orthrough other networks such as access networks) to communicate over thenetwork (e.g., the Internet or virtual private networks (VPNs) overlaidon (e.g., tunneled through) the Internet) with each other (directly orthrough servers) and/or access content and/or services. Such contentand/or services are typically provided by one or more servers (notshown) belonging to a service/content provider or one or more end userdevices (not shown) participating in a peer-to-peer (P2P) service, andmay include, for example, public webpages (e.g., free content, storefronts, search services), private webpages (e.g., username/passwordaccessed webpages providing email services), and/or corporate networksover VPNs. For instance, end user devices may be coupled (e.g., throughcustomer premise equipment coupled to an access network (wired orwirelessly)) to edge NDs, which are coupled (e.g., through one or morecore NDs) to other edge NDs, which are coupled to electronic devicesacting as servers. However, through compute and storage virtualization,one or more of the electronic devices operating as the NDs in FIG. 7Amay also host one or more such servers (e.g., in the case of the generalpurpose network device 704, one or more of the software instances 762A-Rmay operate as servers; the same would be true for the hybrid networkdevice 706; in the case of the special-purpose network device 702, oneor more such servers could also be run on a virtualization layerexecuted by the processor(s) 712); in which case the servers are said tobe co-located with the VNEs of that ND.

A virtual network is a logical abstraction of a physical network (suchas that in FIG. 7A) that provides network services (e.g., L2 and/or L3services). A virtual network can be implemented as an overlay network(sometimes referred to as a network virtualization overlay) thatprovides network services (e.g., layer 2 (L2, data link layer) and/orlayer 3 (L3, network layer) services) over an underlay network (e.g., anL3 network, such as an Internet Protocol (IP) network that uses tunnels(e.g., generic routing encapsulation (GRE), layer 2 tunneling protocol(L2TP), IPSec) to create the overlay network).

A network virtualization edge (NVE) sits at the edge of the underlaynetwork and participates in implementing the network virtualization; thenetwork-facing side of the NVE uses the underlay network to tunnelframes to and from other NVEs; the outward-facing side of the NVE sendsand receives data to and from systems outside the network. A virtualnetwork instance (VNI) is a specific instance of a virtual network on anNVE (e.g., a NE/VNE on an ND, a part of a NE/VNE on a ND where thatNE/VNE is divided into multiple VNEs through emulation); one or moreVNIs can be instantiated on an NVE (e.g., as different VNEs on an ND). Avirtual access point (VAP) is a logical connection point on the NVE forconnecting external systems to a virtual network; a VAP can be physicalor virtual ports identified through logical interface identifiers (e.g.,a VLAN ID).

Examples of network services include: 1) an Ethernet LAN emulationservice (an Ethernet-based multipoint service similar to an InternetEngineering Task Force (IETF) Multiprotocol Label Switching (MPLS) orEthernet VPN (EVPN) service) in which external systems areinterconnected across the network by a LAN environment over the underlaynetwork (e.g., an NVE provides separate L2 VNIs (virtual switchinginstances) for different such virtual networks, and L3 (e.g., IP/MPLS)tunneling encapsulation across the underlay network); and 2) avirtualized IP forwarding service (similar to IETF IP VPN (e.g., BorderGateway Protocol (BGP)/MPLS IPVPN) from a service definitionperspective) in which external systems are interconnected across thenetwork by an L3 environment over the underlay network (e.g., an NVEprovides separate L3 VNIs (forwarding and routing instances) fordifferent such virtual networks, and L3 (e.g., IP/MPLS) tunnelingencapsulation across the underlay network)). Network services may alsoinclude quality of service capabilities (e.g., traffic classificationmarking, traffic conditioning and scheduling), security capabilities(e.g., filters to protect customer premises from network—originatedattacks, to avoid malformed route announcements), and managementcapabilities (e.g., full detection and processing).

FIG. 7D illustrates a network with a single network element on each ofthe NDs of FIG. 7A, and within this straight forward approach contrastsa traditional distributed approach (commonly used by traditionalrouters) with a centralized approach for maintaining reachability andforwarding information (also called network control), according to someembodiments of the invention. Specifically, FIG. 7D illustrates networkelements (NEs) 770A-H with the same connectivity as the NDs 700A-H ofFIG. 7A.

FIG. 7D illustrates that the distributed approach 772 distributesresponsibility for generating the reachability and forwardinginformation across the NEs 770A-H; in other words, the process ofneighbor discovery and topology discovery is distributed.

For example, where the special-purpose network device 702 is used, thecontrol communication and configuration module(s) 732A-R of the NDcontrol plane 724 typically include a reachability and forwardinginformation module to implement one or more routing protocols (e.g., anexterior gateway protocol such as Border Gateway Protocol (BGP),Interior Gateway Protocol(s) (IGP) (e.g., Open Shortest Path First(OSPF), Intermediate System to Intermediate System (IS-IS), RoutingInformation Protocol (RIP), Label Distribution Protocol (LDP), ResourceReservation Protocol (RSVP) (including RSVP-Traffic Engineering (TE):Extensions to RSVP for LSP Tunnels and Generalized Multi-Protocol LabelSwitching (GMPLS) Signaling RSVP-TE)) that communicate with other NEs toexchange routes, and then selects those routes based on one or morerouting metrics. Thus, the NEs 770A-H (e.g., the processor(s) 712executing the control communication and configuration module(s) 732A-R)perform their responsibility for participating in controlling how data(e.g., packets) is to be routed (e.g., the next hop for the data and theoutgoing physical NI for that data) by distributively determining thereachability within the network and calculating their respectiveforwarding information. Routes and adjacencies are stored in one or morerouting structures (e.g., Routing Information Base (RIB), LabelInformation Base (LIB), one or more adjacency structures) on the NDcontrol plane 724. The ND control plane 724 programs the ND forwardingplane 726 with information (e.g., adjacency and route information) basedon the routing structure(s). For example, the ND control plane 724programs the adjacency and route information into one or more forwardingtable(s) 734A-R (e.g., Forwarding Information Base (FIB), LabelForwarding Information Base (LFIB), and one or more adjacencystructures) on the ND forwarding plane 726. For layer 2 forwarding, theND can store one or more bridging tables that are used to forward databased on the layer 2 information in that data. While the above exampleuses the special-purpose network device 702, the same distributedapproach 772 can be implemented on the general-purpose network device704 and the hybrid network device 706.

FIG. 7D illustrates that a centralized approach 774 (also known assoftware defined networking (SDN)) that decouples the system that makesdecisions about where traffic is sent from the underlying systems thatforwards traffic to the selected destination. The illustratedcentralized approach 774 has the responsibility for the generation ofreachability and forwarding information in a centralized control plane776 (sometimes referred to as an SDN control module, controller, networkcontroller, OpenFlow controller, SDN controller, control plane node,network virtualization authority, or management control entity), andthus the process of neighbor discovery and topology discovery iscentralized. The centralized control plane 776 has a south boundinterface 782 with a data plane 780 (sometime referred to theinfrastructure layer, network forwarding plane, or forwarding plane(which should not be confused with a ND forwarding plane)) that includesthe NEs 770A-H (sometimes referred to as switches, forwarding elements,data plane elements, or nodes). The centralized control plane 776includes a network controller 778, which includes a centralizedreachability and forwarding information module 779 that determines thereachability within the network and distributes the forwardinginformation to the NEs 770A-H of the data plane 780 over the south boundinterface 782 (which may use the OpenFlow protocol). Thus, the networkintelligence is centralized in the centralized control plane 776executing on electronic devices that are typically separate from theNDs.

For example, where the special-purpose network device 702 is used in thedata plane 780, each of the control communication and configurationmodule(s) 732A-R of the ND control plane 724 typically include a controlagent that provides the VNE side of the south bound interface 782. Inthis case, the ND control plane 724 (the processor(s) 712 executing thecontrol communication and configuration module(s) 732A-R) performs itsresponsibility for participating in controlling how data (e.g., packets)is to be routed (e.g., the next hop for the data and the outgoingphysical NI for that data) through the control agent communicating withthe centralized control plane 776 to receive the forwarding information(and in some cases, the reachability information) from the centralizedreachability and forwarding information module 779 (it should beunderstood that in some embodiments of the invention, the controlcommunication and configuration module(s) 732A-R, in addition tocommunicating with the centralized control plane 776, may also play somerole in determining reachability and/or calculating forwardinginformation—albeit less so than in the case of a distributed approach;such embodiments are generally considered to fall under the centralizedapproach 774, but may also be considered a hybrid approach). Thecentralized control plane 776 can include the event handler and/or eventcollector 781 as described herein or aspects thereof as part of the NFVsoftware and infrastructure that is managed by the centralized controlplane 776.

While the above example uses the special-purpose network device 702, thesame centralized approach 774 can be implemented with the generalpurpose network device 704 (e.g., each of the VNE 760A-R performs itsresponsibility for controlling how data (e.g., packets) is to be routed(e.g., the next hop for the data and the outgoing physical NI for thatdata) by communicating with the centralized control plane 776 to receivethe forwarding information (and in some cases, the reachabilityinformation) from the centralized reachability and forwardinginformation module 779; it should be understood that in some embodimentsof the invention, the VNEs 760A-R, in addition to communicating with thecentralized control plane 776, may also play some role in determiningreachability and/or calculating forwarding information—albeit less sothan in the case of a distributed approach) and the hybrid networkdevice 706. In fact, the use of SDN techniques can enhance the NFVtechniques typically used in the general-purpose network device 704 orhybrid network device 706 implementations as NFV is able to support SDNby providing an infrastructure upon which the SDN software can be run,and NFV and SDN both aim to make use of commodity server hardware andphysical switches.

FIG. 7D also shows that the centralized control plane 776 has a northbound interface 784 to an application layer 786, in which residesapplication(s) 788. The centralized control plane 776 has the ability toform virtual networks 792 (sometimes referred to as a logical forwardingplane, network services, or overlay networks (with the NEs 770A-H of thedata plane 780 being the underlay network)) for the application(s) 788.Thus, the centralized control plane 776 maintains a global view of allNDs and configured NEs/VNEs, and it maps the virtual networks to theunderlying NDs efficiently (including maintaining these mappings as thephysical network changes either through hardware (ND, link, or NDcomponent) failure, addition, or removal).

While FIG. 7D shows the distributed approach 772 separate from thecentralized approach 774, the effort of network control may bedistributed differently or the two combined in certain embodiments ofthe invention. For example: 1) embodiments may generally use thecentralized approach (SDN) 774, but have certain functions delegated tothe NEs (e.g., the distributed approach may be used to implement one ormore of fault monitoring, performance monitoring, protection switching,and primitives for neighbor and/or topology discovery); or 2)embodiments of the invention may perform neighbor discovery and topologydiscovery via both the centralized control plane and the distributedprotocols, and the results compared to raise exceptions where they donot agree. Such embodiments are generally considered to fall under thecentralized approach 774 but may also be considered a hybrid approach.

While FIG. 7D illustrates the simple case where each of the NDs 700A-Himplements a single NE 770A-H, it should be understood that the networkcontrol approaches described with reference to FIG. 7D also work fornetworks where one or more of the NDs 700A-H implement multiple VNEs(e.g., VNEs 730A-R, VNEs 760A-R, those in the hybrid network device706). Alternatively, or in addition, the network controller 778 may alsoemulate the implementation of multiple VNEs in a single ND.Specifically, instead of (or in addition to) implementing multiple VNEsin a single ND, the network controller 778 may present theimplementation of a VNE/NE in a single ND as multiple VNEs in thevirtual networks 792 (all in the same one of the virtual network(s) 792,each in different ones of the virtual network(s) 792, or somecombination). For example, the network controller 778 may cause an ND toimplement a single VNE (a NE) in the underlay network, and thenlogically divide up the resources of that NE within the centralizedcontrol plane 776 to present different VNEs in the virtual network(s)792 (where these different VNEs in the overlay networks are sharing theresources of the single VNE/NE implementation on the ND in the underlaynetwork).

On the other hand, FIGS. 7E and 7F respectively illustrate exemplaryabstractions of NEs and VNEs that the network controller 778 may presentas part of different ones of the virtual networks 792. FIG. 7Eillustrates the simple case of where each of the NDs 700A-H implements asingle NE 770A-H (see FIG. 7D), but the centralized control plane 776has abstracted multiple of the NEs in different NDs (the NEs 770A-C andG-H) into (to represent) a single NE 7701 in one of the virtualnetwork(s) 792 of FIG. 7D, according to some embodiments of theinvention. FIG. 7E shows that in this virtual network, the NE 7701 iscoupled to NE 770D and 770F, which are both still coupled to NE 770E.

FIG. 7F illustrates a case where multiple VNEs (VNE 770A.1 and VNE770H.1) are implemented on different NDs (ND 700A and ND 700H) and arecoupled to each other, and where the centralized control plane 776 hasabstracted these multiple VNEs such that they appear as a single VNE770T within one of the virtual networks 792 of FIG. 7D, according tosome embodiments of the invention. Thus, the abstraction of a NE or VNEcan span multiple NDs.

While some embodiments of the invention implement the centralizedcontrol plane 776 as a single entity (e.g., a single instance ofsoftware running on a single electronic device), alternative embodimentsmay spread the functionality across multiple entities for redundancyand/or scalability purposes (e.g., multiple instances of softwarerunning on different electronic devices).

Similar to the network device implementations, the electronic device(s)running the centralized control plane 776, and thus the networkcontroller 778 including the centralized reachability and forwardinginformation module 779, may be implemented a variety of ways (e.g., aspecial purpose device, a general-purpose (e.g., COTS) device, or hybriddevice). These electronic device(s) would similarly includeprocessor(s), a set or one or more physical NIs, and a non-transitorymachine-readable storage medium having stored thereon the centralizedcontrol plane software. For instance, FIG. 8 illustrates, ageneral-purpose control plane device 804 including hardware 840comprising a set of one or more processor(s) 842 (which are often COTSprocessors) and physical NIs 846, as well as non-transitorymachine-readable storage media 848 having stored therein centralizedcontrol plane (CCP) software 850. The non-transitory machine readablestorage media can store the event handler and/or event collector 881 asdescribed herein as part of the NFV software and infrastructure.

In embodiments that use compute virtualization, the processor(s) 842typically execute software to instantiate a virtualization layer 854(e.g., in one embodiment the virtualization layer 854 represents thekernel of an operating system (or a shim executing on a base operatingsystem) that allows for the creation of multiple instances 862A-R calledsoftware containers (representing separate user spaces and also calledvirtualization engines, virtual private servers, or jails) that may eachbe used to execute a set of one or more applications; in anotherembodiment the virtualization layer 854 represents a hypervisor(sometimes referred to as a virtual machine monitor (VMM)) or ahypervisor executing on top of a host operating system, and anapplication is run on top of a guest operating system within an instance862A-R called a virtual machine (which in some cases may be considered atightly isolated form of software container) that is run by thehypervisor; in another embodiment, an application is implemented as aunikernel, which can be generated by compiling directly with anapplication only a limited set of libraries (e.g., from a libraryoperating system (LibOS) including drivers/libraries of OS services)that provide the particular OS services needed by the application, andthe unikernel can run directly on hardware 840, directly on a hypervisorrepresented by virtualization layer 854 (in which case the unikernel issometimes described as running within a LibOS virtual machine), or in asoftware container represented by one of instances 862A-R). Again, inembodiments where compute virtualization is used, during operation aninstance of the CCP software 850 (illustrated as CCP instance 876A) isexecuted (e.g., within the instance 862A) on the virtualization layer854. In embodiments where compute virtualization is not used, the CCPinstance 876A is executed, as a unikernel or on top of a host operatingsystem, on the “bare metal” general purpose control plane device 804.The instantiation of the CCP instance 876A, as well as thevirtualization layer 854 and instances 862A-R if implemented, arecollectively referred to as software instance(s) 852.

In some embodiments, the CCP instance 876A includes a network controllerinstance 878. The network controller instance 878 includes a centralizedreachability and forwarding information module instance 879 (which is amiddleware layer providing the context of the network controller 778 tothe operating system and communicating with the various NEs), and an CCPapplication layer 880 (sometimes referred to as an application layer)over the middleware layer (providing the intelligence required forvarious network operations such as protocols, network situationalawareness, and user—interfaces). At a more abstract level, this CCPapplication layer 880 within the centralized control plane 776 workswith virtual network view(s) (logical view(s) of the network) and themiddleware layer provides the conversion from the virtual networks tothe physical view.

The centralized control plane 776 transmits relevant messages to thedata plane 780 based on CCP application layer 880 calculations andmiddleware layer mapping for each flow. A flow may be defined as a setof packets whose headers match a given pattern of bits; in this sense,traditional IP forwarding is also flow—based forwarding where the flowsare defined by the destination IP address for example; however, in otherimplementations, the given pattern of bits used for a flow definitionmay include more fields (e.g., 10 or more) in the packet headers.Different NDs/NEs/VNEs of the data plane 780 may receive differentmessages, and thus different forwarding information. The data plane 780processes these messages and programs the appropriate flow informationand corresponding actions in the forwarding tables (sometime referred toas flow tables) of the appropriate NE/VNEs, and then the NEs/VNEs mapincoming packets to flows represented in the forwarding tables andforward packets based on the matches in the forwarding tables.

Standards such as OpenFlow define the protocols used for the messages,as well as a model for processing the packets. The model for processingpackets includes header parsing, packet classification, and makingforwarding decisions. Header parsing describes how to interpret a packetbased upon a well-known set of protocols. Some protocol fields are usedto build a match structure (or key) that will be used in packetclassification (e.g., a first key field could be a source media accesscontrol (MAC) address, and a second key field could be a destination MACaddress).

Packet classification involves executing a lookup in memory to classifythe packet by determining which entry (also referred to as a forwardingtable entry or flow entry) in the forwarding tables best matches thepacket based upon the match structure, or key, of the forwarding tableentries. It is possible that many flows represented in the forwardingtable entries can correspond/match to a packet; in this case the systemis typically configured to determine one forwarding table entry from themany according to a defined scheme (e.g., selecting a first forwardingtable entry that is matched). Forwarding table entries include both aspecific set of match criteria (a set of values or wildcards, or anindication of what portions of a packet should be compared to aparticular value/values/wildcards, as defined by the matchingcapabilities—for specific fields in the packet header, or for some otherpacket content), and a set of one or more actions for the data plane totake on receiving a matching packet. For example, an action may be topush a header onto the packet, for the packet using a particular port,flood the packet, or simply drop the packet. Thus, a forwarding tableentry for IPv4/IPv6 packets with a particular transmission controlprotocol (TCP) destination port could contain an action specifying thatthese packets should be dropped.

Making forwarding decisions and performing actions occurs, based uponthe forwarding table entry identified during packet classification, byexecuting the set of actions identified in the matched forwarding tableentry on the packet.

However, when an unknown packet (for example, a “missed packet” or a“match-miss” as used in OpenFlow parlance) arrives at the data plane780, the packet (or a subset of the packet header and content) istypically forwarded to the centralized control plane 776. Thecentralized control plane 776 will then program forwarding table entriesinto the data plane 780 to accommodate packets belonging to the flow ofthe unknown packet. Once a specific forwarding table entry has beenprogrammed into the data plane 780 by the centralized control plane 776,the next packet with matching credentials will match that forwardingtable entry and take the set of actions associated with that matchedentry.

While the invention has been described in terms of several embodiments,those skilled in the art will recognize that the invention is notlimited to the embodiments described, can be practiced with modificationand alteration within the spirit and scope of the appended claims. Thedescription is thus to be regarded as illustrative instead of limiting.

1. A method implemented by an event collector to utilize feedback froman event handler to prioritize event forwarding to the event handler,the method comprising: receiving feedback from the event handler inresponse to a successful match-action in a rules engine, the feedbackincluding a derived condition which is a generalized version of acondition stored in a match part of a rule; determining whether thederived condition is stored in an event prioritizer; storing the derivedcondition in the event prioritizer with initial expiration timer and hitcounter, in response to the derived condition not being present in theevent prioritizer; and updating the hit counter and expiration timer ofthe derived condition in the event prioritizer, in response to thederived condition being present in the event prioritizer.
 2. The methodof claim 1, further comprising: resetting an expiration timer of aderived condition in response to receiving a subsequent occurrence ofthe derived condition.
 3. The method of claim 2, further comprising:incrementing the hit counter in response to receiving the subsequentoccurrence of the derived condition.
 4. The method of claim 1, furthercomprising: prioritizing received events using a priority value based onmatching derived conditions.
 5. The method of claim 4, wherein thepriority value is a sum, median, mean, or mode of the hit counter ofmatching derived conditions.
 6. The method of claim 1, furthercomprising: storing received events in one of a set of priority queuesto be dispatched to the event handler.
 7. The method of claim 1, furthercomprising: determining a priority queue to source a next event fromusing a pre-configured policy; and forwarding a next event from thepriority queue.
 8. The method of claim 1, further comprising: processingan event by a rules engine and executing actions matching the event. 9.The method of claim 8, further comprising: determining the derivedcondition for a matched rule.
 10. A computing device to implement amethod of an event collector to utilize feedback from an event handlerto prioritize event forwarding to the event handler, the computingdevice comprising: a non-transitory machine-readable medium havingstored therein the event collector; and a processor coupled to thenon-transitory machine-readable medium, the processor to execute theevent collector, the event collector to receive feedback from the eventhandler in response to a successful match-action in a rules engine, thefeedback including a derived condition which is a generalized version ofa condition stored in a match part of a rule, to determine whether thederived condition is stored in an event prioritizer, to store thederived condition in the event prioritizer with initial expiration timerand hit counter, in response to the derived condition not being presentin the event prioritizer, and to update the hit counter and theexpiration timer of the derived condition in the event prioritizer, inresponse to the derived condition being present in the eventprioritizer.
 11. The computing device of claim 10, wherein the eventcollector resets an expiration timer of a derived condition in responseto receiving a subsequent occurrence of the derived condition.
 12. Thecomputing device of claim 11, wherein the event collector increments thehit counter in response to receiving the subsequent occurrence of thederived condition.
 13. The computing device of claim 10, wherein theevent collector prioritizes received events using a priority value basedon matching derived conditions.
 14. The computing device of claim 13,wherein the priority value is a sum, median, mean, or mode of the hitcounter of matching derived conditions.
 15. The computing device ofclaim 10, wherein the event collector stores received events in one of aset of priority queues to be dispatched to the event handler.
 16. Thecomputing device of claim 10, further comprising: an event handler todetermine a priority queue to source a next event from using apre-configured policy, and to forward a next event from the priorityqueue.
 17. The computing device of claim 16, wherein the event handlerprocesses an event by a rules engine and executing actions matching theevent.
 18. The computing device of claim 17, wherein the event handlerfurther determines the derived condition for a matched rule.